The purpose of this project is to study the hypoxic cell radiosensitizer misonidazole in conjunction with radiation therapy in the treatment of locally unresectable osteogenic sarcoma and chondrosarcoma. Patients who have a local neoplasm for which no radical surgery can be successfully undertaken will be treated with fractionation radiation therapy in conjunction with intravenously administered misonidazole. Because of the small number of patients who are appropriate for such a study, this will be a one armed study. Following completion of radiation therapy, combination chemotherapy will be administered to patients with osteogenic sarcoma with high grade neoplasms. Following completion of all treatment, survival, freedom from relapse, and complications of treatment will be carefully assessed.